1. All cities of the third class in this state may by ordinance levy and impose annually for municipal purposes upon all subjects and objects of taxation within such cities a tax which shall not exceed the maximum rate of one dollar on the one hundred dollars assessed valuation; provided, however, that the rate of tax levy of one dollar on the one hundred dollars assessed valuation for municipal purposes may be increased for such purposes for a period not to exceed four years at any one time when such rate and purpose of increase are submitted to a vote of the voters within such cities and two-thirds of the voters voting thereon shall vote therefor, but such increase so voted shall be limited to a maximum rate of taxation not to exceed thirty cents on the one hundred dollars assessed valuation.

2. The city council may submit the question of increasing the levy when in the opinion of such city council the necessity therefor arises, and the question shall be submitted by such city council when petitioned therefor by voters equaling in number five percent or more of the voters of such cities voting for mayor at the last election at which a mayor was elected.

3. The question shall be submitted in substantially the following form:

Shall there be a ______ cent increase in tax levy on one hundred dollars valuation for general municipal purposes for ______ years in the city of ______?

4. If such increase in levy shall be voted, then such increased levy shall be effective for the number of years designated, and no longer, but cities through their city councils may submit the question of continuing such increase of levy at any time for like periods not to exceed four years each.